It always amazes me how different people's perspectives are while at Disney. We were there this past January, from I think the 19th-28th, or around there, and had absolutely no problem with the weather, except for one night. There were tornado warnings in the area, but it worked well for us as we needed a night in vs. out at a park (because we were pooped!). Other than that, it was not that cold out. We usually found ourselves in t-shirts and shorts during the day, and a hoodie and shorts during the evenings. We went swimming multiple times, as it was in the 70s most days, and even jumped in the pool at GF one night when it was chilly out. I don't mind since the pools are heated and it's tons of fun to go nightswimming when no one else is around.
Crowd-wise, it was amazing. I remember being in awe when we literally walked onto POTC as our first ride, and the CMs gave us our own boat! We also were able to ride EE repeatedly one morning with no wait, etc. We made very good use of an iPhone app in deciding where to go for the day in terms of avoiding crowds. We never did rope drop or FP either because it wasn't necessary. The longest we waited was for TSMM, as that was always busy, and it was around a 40 minute wait. I didn't really get the appeal of that ride, I mean it was fun, but not worth the wait. But yeah, I would never go any other time of the year to WDW... which is why we're going back the same week this January (19th-29th).
If you're smart about what parks you go to and have an idea as to what to avoid each day, you'll be fine and will more than likely be really stoked that you're going at such a slow time. Oh and yes, there are ride closures but having the ability to go on so many rides without lines is a pretty darn good trade-off if you ask me.